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Biomedical subjects

K Schmidt

Publications and source records attributed to K Schmidt.

At least 505 records · Page 28Linked to original sources
PubMed1983

[Effect of radix urticae extract and its several secondary extracts on blood SHBG in benign prostate hyperplasia].

The paper presents studies on the interaction of an extract of radix urticae with the sexual hormone binding globulin of the blood plasma and with the androgen receptor of the prostatic cytosol. It is shown that the binding of 5-alpha-dihydrotestosterone with the binding proteins can be influenced by the extract. The significance of such an interaction to the aetiology and pathogenesis of benign prostatic hyperplasia is discussed. It is likely that such mechanisms participate in the action of conservative treatment of prostatic hyperplasia. The investigations are of great importance in the efforts to place phytotherapy of prostatic hyperplasia on a rational basis. Further investigations are necessary to elucidate the active components of the extracts and to discover the mechanism of action in detail. This could also be an advance in the elucidation of the cause of prostatic hyperplasia.

Humans↗
PubMed1983

Phagocytic activity of granulocytes and alveolar macrophages after burn injury measured by chemiluminescence.

Despite substantial progress in handling the acute phase, about 50 per cent of all severely burned patients are still subject to lethal infections during the later stages of the burn disease. Such patients frequently succumb to infections by opportunistic bacteria and viruses of normally low virulence indicating that the antiinfectious host defences are severely compromised. The present study was conducted in order to evaluate the effects of severe thermal injury on the two major categories of phagocytic cells, the circulating phagocytes of the blood and the alveolar macrophages as one population of the fixed phagocytes of the reticulo-endothelial system. The cells were isolated from burned and unburned rats. For quantitative assessment of the phagocytic function the chemiluminescence associated with the phagocytosis of opsonized zymosan particles was measured, using luminol as a chemiluminigenic probe. It turned out that as a consequence of the thermal trauma the phagocytic activity as measured by chemiluminescence is reduced in granulocytes as well as in alveolar macrophages.

Animals↗
PubMed1983

[New aspects of the treatment of larger bone defects].

A characterisation of mainly used implant materials into bone defects is performed. The materials are classified in two groups; their biological effects are described in detail. Using OCG as a typical osteoinductive implant histological and radiological findings are described which take place in animals after heterotopic and orthotopic implantation.

Animals↗
PubMed1983

Studies on the metabolic conversion of ascorbate.

In the intact animal guinea pigs metabolize (1-14C)ascorbic acid much faster to (14C)carbon dioxide (peak exhalation at 30 min) than rats (peak exhalation at 2 to 3 h) following single oral administration, but total excretion was comparable. This finding might be related to the differences in the absorption mechanism of ascorbic acid in these species. The large difference in retention capacity of ascorbic acid in the liver is suggested to be due to multiple recirculation of ascorbic acid in the guinea pig when compared to the rate. Homogenate preparations of rat stomach, small intestine or liver as well as cultured intestinal microbial flora did not cause metabolic degradation on incubation with (1-14C)ascorbic acid to (14C)carbon dioxide. It is therefore suggested that the observed excretion of (14C)carbon dioxide is due to spontaneous non-enzymatical reaction in liver and possible other tissues. Analysis of ascorbic acid metabolites formed on incubation by analytical isotachophoresis suggests that ascorbic acid is a rather stable substrate whereas dehydroascorbate and 2,3-diketogulonic acid are rapidly degraded. This allows the assumption that in vivo metabolism of ascorbic acid might not involve dehydroascorbic acid. Our data do not support the hypothesis that ascorbic acid undergoes presystemic metabolism to carbon dioxide in the intestinal wall.

2,3-Diketogulonic Acid↗
PubMed1983

A high performance liquid chromatographic method for the determination of kinin releasing activity of kallikrein.

An HPLC method for measuring the in vitro kinin-forming activity of Kallikrein (K), is described. Kinins are formed by incubating K with partially purified bovine kininogen. An aliquot portion of the incubation solution is injected directly onto the chromatographic column (RP-18, 10 um, length 25 cm, 4 mm i.d.). Kallidin and bradykinin are separated from each other and ballast substances by gradient elution technique (phosphate buffer, acetonitrile) and column switching. By post column derivatization kinins are reacted with the fluorogenic reagent Fluram and quantified online, using a fluorescence detector. Detection limits for kallidin and bradykinin are approximately 3 ng = 2.5 pico mol. The reproducibility of the results is 2% (relative standard deviation). This method has been used to study the kinin-forming activity of different K formulations and the results were compared with those obtained by bioassay. As a main result the reaction kinetics demonstrate that purified K solely produces kallidin. Bradykinin showing up later in the reaction mixture must be due to impurities of kininogen which convert kallidin to bradykinin. K itself does not convert kallidin to bradykinin.

Animals↗
PubMed1982

Changes of membrane conductance and permeability by constituents of normal and burned skin.

Generation and release of toxic factors from burned tissue is an important pathogenetic mechanism after severe thermal injury. In this paper the interactions between cell membranes or artificial lipid bilayer membranes and burn toxin were studied. It turned out that low concentrations of the toxic material released from dermal tissue by standardized thermal injury or mechanical homogenization create significant permeability changes. The dependence of the effect upon salt concentration, lipid composition, and voltage was investigated. High current resolution experiments did not reveal formation of defined pores. In general, the studies show that burn toxin introduces hydrophilic pathways into cell membranes as well as lipid bilayers. The effects measured in this work are likely to play a major role in the etiology of tissue edema after burns.

Animals↗
PubMed1982

In vitro studies on the interaction between bile salts and key enzymes of the liver.

Interactions between bile salts and cellular constituents are of considerable significance in studies on cholestasis. The main points of interest are the effects of the various bile salts on lipid and protein structures. Of primary interest are the interactions with lipids since these can cause disorder in cellular metabolism by eliminating compartmentalization. Conformational changes of proteins can occur through interactions with bile salts. They can involve specific functions. Of special importance here are the enzymes, since these are decisive supportive agents in cellular processes. In this paper, the effect of various bile salts on the activity of key hepatic enzymes was studied. In addition to the kinetic tests for enzyme activity, structural changes of the enzymes were studied as well using electrophoretic techniques. It could be shown that even much lower bile salt concentrations than those which occur in bile can lead to a complete inhibition of activity. The varying sensitivities of different enzymes when they react in the presence of bile salts is striking. According to the degree of hydroxylation, the various bile salts show characteristic differences in inhibitory effect on enzymatic activity. On the basis of the results reported here, it is quite possible that the interaction between bile salts and enzymes is a participating factor in the etiology and pathogenesis of cholestatic hepatic changes.

Alanine Transaminase↗
PubMed1982

Osteoinduction. Part I: Test model and comparative long term observation of allogenic and xenogenic matrix implants.

In order to demonstrate osteoinductive activity of transplants and implants an experimental approach is presented in this study. Matrix induced osteogenesis following allogenic and xenogenic implantation is demonstrated morphologically, by induction of alkaline phosphatase, and by mineralisation of the newly formed matrix. Beginning on day 20 new bone formation can be found lasting up to 6 months in allogenic implants, whereas in xenogenic implants only inflammatory infiltrations are detectable. Osteoinduction is a matrix conducted phenomenon, as was confirmed by control experiments. Orthotopic allogenic implantation in diaphyseal defects of dogs demonstrates the ability of such implants to bridge a great defect by induced new bone formation and the property of the newly formed bone to adapt to physiologic stress.

Alkaline Phosphatase↗
PubMed1982

Osteoinduction. Part II: Purification of the osteoinductive activities of bone matrix.

Using a previously described experimental model for demonstration of osteoinduction biological activity of variably prepared fractions of demineralized bone matrix was studied. Sequential extraction of matrix using CaCl2, EDTA, LiCl and water results in an acceleration of the induction process and a reduction of immunological host reaction in the case of xenogenic implants. Application of chaotropic reagents such as guanidinium chloride and sodium thiocyanate has the consequency of lowering the inductive signal. From these results it is likely that noncollagenous constituents of bone matrix play a significant role in osteoinduction.

Alkaline Phosphatase↗
PubMed1982

Permeability changes of Ehrlich mouse ascites tumor cells induced by a cytotoxin from Pseudomonas aeruginosa.

Ehrlich ascites tumor cells from mice were damaged during in vitro incubation with a cytotoxin from Pseudomonas aeruginosa at concentrations of greater than 1 microgram/ml. After a short time the cells started to lose potassium whereas their sodium content increased. When the protein concentration of the incubation medium was adjusted to the protein concentration inside the cells, swelling and release of glucose-6-phosphate dehydrogenase was avoided. However, lysis of the cells still took place. Preincubation of cells with tetrodotoxin, 4-aminopyridine or tetraethylammonium did not influence damage to the cells. The cells showed a steep increase in toxin response between 17 degrees and 27 degrees C ranging from insensitivity to full sensitivity. An increase in electrical conductance was measured during incubation of cholesterol bilayer membranes with a cytotoxin concentration of 1 microgram/ml. The conductance was increased by a factor of ten within 30 min at 25 degrees C which indicates the involvement of membrane lipids in the cytotoxin action.

Animals↗
PubMed1982

Effects of peptide hormones on urea- and glycogen-synthesis of isolated hepatocytes and the influence of a toxic factor from burnt mouse and human skin.

A toxic extent has been isolated and partially purified from burnt human and mouse skin and also from sera of severely burnt patients, which causes disturbances of energy metabolism and decreased synthesis rates for glucose and urea in the perfused rat liver. Enzymatically isolated hepatocytes from rat livers were used to study the toxic effects on hormonal sensitivity, synthetic functions and ultrastructure of the cells. A decreased synthesis of urea and glycogen was found in cells from rats treated 5 days before with "toxin" and in cells, which were directly incubated with the toxic factor. Glucagon increased urea synthesis in normal cells by 33%, and a decrease of 25% was caused by insulin. Cells of rats treated with the nontoxic precursor of the toxic factor from normal skin were similar, while those treated with "toxin" produced less urea and did not react to glucagon or insulin. Glycogen synthesis was reduced in cells directly incubated with the "toxin", however, the hormonal effects were still observed. Surface alterations of "toxin" treated cells and cells of "toxin" treated rats were found by scanning electronmicroscopy. These findings provide evidence of a direct cytotoxic effect of the toxic factor from burnt skin. It is proposed that the "toxin" acts on the cellular membrane with destruction of surface and receptorproteins.

Animals↗
PubMed1982

[Hereditary drusen of Bruch's membrane. I. Clinical and light microscopical study ].

The authors describe a family with autosomal-dominant inheritance of hereditary Bruch's membrane drusen. After the death of the proband who was kept under clinical observation with fluorescein-angiographic examination over a period of seven years, the authors obtained the bulbus for histopathologic study. Light microscopic changes in the boundary-line structures of the retina and choroid and the occurrence of an intraretinal membrane in the maculopapillary bunch area are described. This membrane is thought to represent a "predisciform stage" in the development of this hereditary dystrophy.

Adolescent↗